Generally, keyboards, touchpads, mice and other input devices have built-in irreplaceable wired communication chips (e.g., USB communication chips) or wireless communication chips (e.g., Bluetooth communication chips). Moreover, since these input devices cannot be connected with other external devices, the functions are not expandable. In other words, the conventional input devices are not user-friendly. For example, if a user intends to use both of a wired keyboard and a wireless keyboard, the user has to purchase two keyboards that have different communication chips but have the same function. Moreover, after the user purchases the keyboards, the original functions of the keyboards cannot be expanded through other externals devices. Instead, for expanding the functions, the user has to purchase other devices and connect these devices with an electronic device. However, the above approaches increase the additional cost, and it is difficult to carry and store these devices.
For solving the above drawbacks, an input system capable of connecting to other external devices to expand the functions has been introduced into the market. FIG. 1 is a schematic exploded view illustrating a conventional function-expandable input system and taken along a front viewpoint. FIG. 2 is a schematic exploded view illustrating the conventional function-expandable input system of FIG. 1 and taken along a rear viewpoint. This input system is disclosed in U.S. Pat. No. 6,504,709 for example. As shown in FIGS. 1 and 2, the conventional input system 10 comprises a keyboard 11 and four external devices 12. An accommodation space 13 is formed in a rear side of the keyboard 11. A circuit board 14 is disposed within the accommodation space 13. The four external devices 12 are connected with four connecting ports 15, respectively. The four external devices 12 and a connecting wire 16 are electrically connected with the circuit board 14. The connecting wire 16 is connected with an electronic device (not shown). Consequently, the keyboard 11 and the four external devices 12 are in communication with the electronic device in order to input characters or implement associated tasks and expand the functions.
As mentioned above, the conventional input system 10 is connected with the electronic device through the connecting wire 16 only. That is, the user cannot replace the communication chip to change the way of connecting the input system 10 and the electronic device according to the practical requirements. Moreover, the user cannot use the external device 12 individually or expand the functions thereof. Even if the user only intends to use the external device 12, the external device 12 still needs to be connected with the keyboard 11 before use. In other words, the conventional input system 10 cannot solve the above drawbacks (e.g., the additional cost and the carrying and storing difficulty).
Therefore, there is a need of providing an improved input system in order to overcome the above drawbacks.